Artificial Satellites

Many objects like stars, satellites and the moon are visible in the night sky. Satellites are objects revolving around the planet or a more significant object. Moon is the most commonly observed satellite. Moon is a satellite of the earth because the moon revolves around the earth in a fixed orbit. 

What is a Satellite?  

A satellite is an artificial or natural object revolving around the planet or a more significant object in the outer space. It revolves around the earth in a particular orbit or axis. There are lots of satellites available in our solar system. Moon is one of the most popular satellites of the earth in our solar system.

There are two types of satellites present in our solar system. These are as follows:

1. Natural Satellites.
2. Artificial or Man-made satellite.

1. Natural Satellites

Any celestial body such as the sun, planet, star, or moon that revolve around the earth or a more significant object in outer space is called a natural satellite. There are six planetary satellite systems, and 205 satellites are known as natural satellites in our solar system. These satellites revolve in a larger orbit. The surface of these natural satellites is made up of rocky mountains or gases. 

Example: Earth has a natural satellite known as the moon, revolving around the earth in a fixed orbit. Similarly, Earth, Venus, Neptune etc. revolve around the sun.

2. Artificial Satellite

An object which is manufactured by people and sent the outer space with the help of a rocket for research purpose is known as an artificial satellite. Currently, there are many active satellites which are revolving around the earth. The design, altitude and size of the satellite depend on the use of the satellite. These satellites consist of many cameras and essential instruments. These satellites are made to revolve around the planets in a prefixed orbit, revolving close to the world. These are sent to outer space from the earth with the help of a rocket. 

Example: Sputnik-1 is the world's first artificial intelligence satellite launched on 4th October 1957 by the Soviet Union. It was 58 cm in diameter and 83.6kg in weight, and it revolves around the earth in 98 minutes. After that, 8900 satellites were sent from more than 50 countries. According to estimates, there are only 5000 available. Out of 5000, only 1900 were operational. The other satellite is useless, and these will be present in space till their destruction. Yuri Gagarin was the first person who travelled to space. He was from the Soviet Union. Lyka was the first animal to travel in space. 

Indian Progress

Aryabhata was India's first artificial satellite, launched on 19th April 1975. It was sent to outer space by a Russian rocket named SOYUZ from the Russian launch pad. Some other Artificial Satellite which are INSAT (Indian National Satellite), IRS (Indian Remote sensing Satellite), Kalpana-1, Gsat and Edusat etc. In INDIA, there is space research named ISRO (Indian Space Research Organization). CHANDRAYAN project is a great success for India. Its primary purpose is to find the existence of water on the moon, and CHANDRAYAN got successful on that mission in the first attempt. Then INDIA launched a Mangalyan to mars which was also successful. Indian satellites are launched to space from Sriharikota near Andhra Pradesh. It is also called as Satish Dhawan Space Centre. India has also developed rockets by which the satellites are projected to space. These rockets are ASLV (Augmented Satellite Launch Vehicle) and SLV (Satellite Launch Vehicle). GSLV (Geostationary Satellite Launch Vehicle). Using these technologies, India has developed missiles like AGNI, PRITHVI, Akash, and Nag, with a range of 5000km. 

The first Indian astronaut Rakesh Sharma travelled to space. And Kalpana Chawla was the first Indian origin who worked in space. 

Use of Artificial Satellite 

1. With the help of Artificial Satellite, we can make contact with space.
2. It is also used for weather forecasting.
3. It is also used to conduct space research.
4. For telecommunication and broadcasting programs.
5. Making of maps.
6. It is also used to implement education programs.

Types of Satellite

1. Communication Satellite

The satellite moving around the earth in the same direction as rotating the earth in 24 hours is called a communication satellite. These satellites are moving around the earth from the earth's surface at a distance of approximately 36000 km. This communication satellite is also known as the geostationary or geosynchronous satellite.

Example: INSAT series satellite.

Use of Communication Satellite:

• These satellites are used to send signals from one place to another.
• Weather forecasting is also done by this satellite.
• Detection of the location of water and ores area can be done by this satellite.
• Spying in the enemy area is also possible with the help of this satellite.

2. Remote Sensing Satellite

Remote sensing satellites are present above the earth's surface at a distance of 480km. These satellites consist of a camera which is used to scan the planet. It sends the information about soil to the base station on earth, where the data is analyzed. 

3. Polar Satellite

These satellites are low orbit satellites that revolve around the earth by passing the north and south poles. These satellites are moving in an orbit called a polar orbit. The polar orbit and equatorial plane make 90 degrees of inclination with each other. These satellites are 500-800 km from the earth's surface. Its period is about 100 minutes.

Use of polar satellite:

• Polar satellites gathers some helpful information which is very important for remote sensing and environmental studies.
• Spying and surveillance can be done through this satellite.
• It is used for monitoring military activities.
• These are also used to record sea temperature.
• These are also used to monitor crop growth.

Global Positioning System (GPS)

The global positioning system is a part of a satellite through which satellite can give the exact longitude, latitude and altitude of a place where the person is. This system is used for navigation propose of ships, aeroplanes etc. India has developed NAVIC as its navigation system.

Space Telescope

It is a satellite which is used for observation in space. The Hubble telescope is an example of a space telescope. It observes different ranges of radiation from outer space. Chandra X-ray observatory is another example of a space satellite. 

The moon is not a communication satellite. Because it does not revolve around the earth in an equatorial plane, its period is not 24 hours. The moon is very far from the planet. So the moon is not used as a communication satellite.

Space Junk

Nearly 8000 objects revolve around the earth. Not all of them are working satellites. Such non-working thing in space revolving around the planet is called space junk. These space junks revolve around the earth at a speed of 27000 km per hour. These space junk can damage the working satellites. 

Radio Telescope

It is also known as GMRT. GMRT stands for Giant Meterwave Radio Telescope. The Tata Institute of Fundamental Research sets it up. With this telescope, studying the planet and solar system can be possible.

There are some other satellites which are categorized based on their application. These are as follows.

1. Global positioning satellite.
2. Navigation satellite.
3. Remote sensing satellite.
4. International space station
5. Astronomical satellite.
6. Earth observation satellite.
7. Military satellite.
8. Weather satellite.
9. Communication satellite etc.

Natural Satellites vs. Artificial Satellites

Natural Satellites	Artificial Satellites
1. These are natural occurring satellites. 2. The human cannot control the natural satellites. 3. We cannot communicate with natural satellites. 4. These are made by natural material like gases, rocks, minerals, water etc. 5. These natural satellites have no lights of their own.	1. These are man-made. 2. These are controlled by human.   3. We can control the artificial satellites.   4. These are made up of metals and other electronic items. 5. These are man-made satellites so these are operated by electricity which is generated through solar panel.

Geostationary Satellites vs. Polar orbiting Satellites

Geostationary Satellites	Polar orbiting satellite
1. These are revolving in equatorial plane. 2. it take 24 hours to complete one circle of the earth. 3. it is situated at a height of 36000 km from earth surface. 4. It is used for telecommunication and weather forecasting.	1 These are revolving in polar orbit of earth. 2. It takes less time to complete one circle of the earth. 3. It is situated at a height of 500-800 km from earth surface. 4. It is used for remote sensing, science and environment related study.